<button class='iconButton'
        ng-class='muteIcon'
        ng-click='onClickMute()'
        ng-focus='onMuteButtonFocus()'
        ng-blur='onMuteButtonLoseFocus()'
        ng-keydown='onMuteButtonKeyDown($event)'
        aria-label='Mute'
        type='button'>
</button>
